Aspects of the present disclosure relate generally to wireless communications and, more particularly, to apparatus and methods of managing signaling radio bearer (SRB) transmissions at a user equipment (UE).
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
A UE communicating with a UMTS network may operate in a non-scheduled mode or in a scheduled mode with respect to transmitting information. For example, in the non-scheduled mode, the UE may be allowed to send only up to a fixed amount of information (referred to as a grant) in a given transmission time interval (TTI). In contrast, in the scheduled mode, the amount of information the UE may send, e.g., the grant, in a TTI may vary based on a number of factors, but in some non-limiting cases may be reduced to zero. The information that the UE transmits may include SRB packets and data packets. For example, the SRB packets may include Access Stratum (AS) and/or Non-Access Stratum (NAS) signaling information related to one or more signaling messages, such as, but not limited to, measurement report messages, reconfiguration messages, or an AS or NAS related messages. Further, for example, the data packet may include circuit-switched (CS) and/or packet-switched (PS) data.
Because of the importance of the SRB packets in maintaining the communication between the UE and the network, the performance of the UE and/or the network may be compromised when SRB packets are not transmitted in a timely manner. For example, when the UE is operating in the scheduled mode and the grant is reduced to zero, the UE operating according to currently available solutions is prohibited from transmitting a pending SRB packet. As such, the UE may experience delays in sending SRB packets to the network, which may lead to less than optimal communication between the UE and the network, or possibly a call drop when the zero-grant condition persists. As such, improvements in managing the transmission of SRB packets from the UE are desired.